var txt = ""
window.onload = function() {
	var str = ""
	var sp1 = document.getElementById("sp1")
	for(var i = 0; i < 4; i++) {
		var num = parseInt(Math.random() * 75) + 48
		if(num >= 58 && num <= 64 || num >= 91 && num <= 96) {
			i--
		} else {
			str += "&#" + num + ";"
		}
	}
	sp1.innerHTML = str;
}

function likai(t) {
	txt = t.value;
	return txt;
}

function queren() {
	var sp1 = document.getElementById("sp1")
	if(txt.toLowerCase() == sp1.innerHTML.toLowerCase()) {
		alert("输入正确")
	} else {
		alert("输入错误")
	}
}